Bulldozer



ug- 29, 1967 G. A. FISHER 3,337,974

BULLDOZER Filed Dec. l6, 1964 3 Sheets-Sheet l IN VEN TOR.

G. A. FISHER Aug. 29, 1967 BULLDOZER 5 Sheets-Shet 3 Filed Dec. 16, 1964INVENTOR. Geo/ye fl; @1 61 BY A'TTORNEV 3,337,974 Patented Aug. 29, 19673,337,974 BULLDOZER George A. Fisher, Mentor on the Lake, Ohio, assignorto General Motors Corporation, Detroit, Mich., a corporation of DelawareFiled Dec. 16, 1964, Ser. No. 418,791 3 Claims. (Cl. 37-144) ABSTRACT OFTHE DISCLOSURE A bulldozer linkage assembly of the parallelogram typewhich is operative through fluid pressure poweroperated cylinders toangle the blade about a longitudinal axis of the vehicle, to pitch theblade about a transverse axis, and to raise the blade.

This invention relates generally to bulldozers and more particularly toa quadrangular or parallelogram linkage which operatively connects theblade element with the vehicle. a

It is not new to utilize a parallelogram type linkage for purposes ofsupporting a dozer blade, and one example of this type of arrangementcan be seen in United States Patent No. 2,974,430, filed Apr. 8, 1957,in the name of Ralph I. Bernotas and assigned to the assignee of thisinvention. More specifically, the linkage shown in the aforementionedpatent comprises a pair of support arms located in substantiallyparallel planes which are connected at spaced points to the vehicle andthe dozer blade. An hydraulically actuated double-acting jack is mountedon the vehicle and connects with the blade for positioning the latterbetween a dozing and carry position.

One advantage of this type of linkage is that it permits the dozer bladeto be raised to a carry position while maintaining'the blade in avertical plane so that during a material stockpiling operation thematerial is more efl'lciently piled toward the top of the heap. In otherwork, such as in heavy pioneering work, the dozer blade can be raised toprovide its full surface for striking trees and other objects which areto be removed at points above the ground so that increased leverage isapplied during the operation.

The linkage as shown in the above-mentioned patent is capable ofpositioning the blade as aforedescribed; however, where it is desired topitch or angle the blade, for example for a ditching or crowningoperation, such positioning cannot be realized without substitutinglinks of different lengths or "as in the'case of the above linkage,without requiring manual adjustment of screw means provided for theangling position. As should be apparent in any earth-moving operation,it is important to have the blade adjustable quickly so that the machinecan be efiiciently utilized.

Another disadvantage of the typical parallelogram linkage utilized forsupporting dozer blades is that the linka'ge tends to sufier frominherent instability whenever the blade is angled for ditching orcrowning work.

Accordingly, one object of the present invention is to provide abulldozer linkage assembly of the parallelogram type which is operativethrough fluid pressure poweroperated cylinders to angle the blade abouta longitudinal axis of the vehicle, to pitch the blade about atransverse axis, and to raise the blade; all the operations beingaccomplished without requiring the vehicle operator to leave thevehicle.

Another object of the present invention is to provide a parallelogramtype linkage for a bulldozer assembly that is stable during all normalwork operations for a dozer.

The above objects and others are accomplished with a dozer assemblymounted on the front of a tractor type vehicle and comprising a pair oftransversely spaced push arms pivotally connected at one end thereof tothe vehicle for movement about a first transverse pivot axis. A dozerblade is mounted to the other ends of the push arms for pivotal movementabout a second transverse axis and a fluid operated double-acting jackextends between each of the push arms and the vehicle for raising andlowering the blade between carry and dozing positions. A strut member isprovided in a plane substantially parallel to that of the push arms andextends between the dozer blade and the vehicle. In the preferred form,the strut member takes the form of a double-acting jack which serves topitch the dozer blade fore and aft about its pivotal connectionwith itspush arms. All pivotal connections between 'the linkage of 'the vehicleand the dozer blade are universal connections thereby permitting theblade to be angled about the longitudinal axis of the vehicle wheneverone of the push arm jacks is extended and the other is contracted.

A more complete understanding of the invention can be derived from thefollowing detailed description when taken in conjunction with thedrawings in which:

FIGURE 1 is an elevational view showing a rubbertired tractor equippedwith a bulldozer linkage assembly made in accordance with thisinvention;

FIGURE 2 is a view taken on line 2-2 of FIG- URE 1;

FIGURE 3 is a front elevational view of the vehicle of FIGURE 1 andillustrates two of the positions of the blade, and

FIGURE 4 is an enlarged view of the bulldozer linkage assembly andillustrates the various positions of the dozer blade.

Referring now to the drawings and more specifically to FIGURES 1, 2 and3 thereof, a rubber-tired tractor or vehicle is shown comprising a body10 having an operators station 12 provided thereon. The forward portionof the body supports a dozer assembly 14 made in accordance with theinvention, which as seen in FIG- URES 2 and 3 comprises a pair of pusharms 16 and 18 located inboard of the front wheels and mounted at theirrespective inner ends by transversely aligned universal connections 20and 22. The push arm 16 includes an elongated rod portion 24 that isconnected to a C- .shaped frame 26 that extends forwardly and pivotallysupports one end of a dozer blade 28 through pivotal connections 30 and32. The push arm 18 is identical in construction to the push arm 16 andtherefore also comprises a rod portion 34 fixed to a C-frame 36 which,in this case, supports the other end of the dozer blade through pivotalconnections 38 and 40. As should be apparent, the pivotal connectionsbetween the C-frames and the dozer blade are axially aligned andtherefore located on a common transverse axis about which the dozerblade may be pitched forwardly-and rearwardly in a manner to bedescribed.

A pair of double-acting hydraulic jacks 42 and 44 are also providedbetween the dozer blade and the vehicle with the cylinder ends of therespective iacks being connected by ball and socket connections 46 and48 to the C-frames 16 and 18. The rod ends of the respective jacks arealso connected by ball and socket connections 50 and 52 to the vehicleat points located vertically above the universal connections between thepush arms and the vehicle. In addition, a double-acting hydraulic tiltjack 54 is located in a plane parallel to the planes of the push armsand also extends between the vehicle and the dozer blade. In thisconnection, it can be seen in FIGURE 1 that the tilt jack 54 isconnected by a ball and socket connection 56 to the vehicle at a pointlying on a transverse horizontal axis that passes through the centers ofthe universal connections 50 and 52. A similar ball and socketconnection 58 joins the forward end of the jack 54 with the upperportion of the blade 28 midway between the ends thereof. Thus, asevidenced from the drawings, the above-described arrangement of pusharms, tilt and lift jacks provides a parallelogram type linkage whichpermits the dozer blade to be raised from a fully lowered to a fullyraised position while maintaining substantially the same position withrespect to the ground and the vehicle as seen in FIGURE 4.

As aforementioned, all of the hydraulic jacks incorporated with thisinvention are of the double-acting type comprising the usual piston andcylinder construction which permits them to be extended and contractedunder power by pressuring one end of the cylinder while venting theother.

In addition, it will be noted that the jacks form part of a hydrauliccircuit that includes the usual pump, reservoir, and fluid directionalcontrol valve; the latter being located at the drivers station anddesignated by the numeral 60. This circuit and the variousinterconnections therein are of conventional design and well known tothose skilled in the art.

It will be noted that by universally connecting the jacks 42, 44 and 54between the vehicle and the dozer blade and similarly providingconnections of this sort between the push arms and the vehicle, thedozer blade 28 may be moved to various positions and still maintain thestability required for various operations. For example, by concurrentcontraction of the lift jacks 42 and 44, the dozer blade 28 can be movedfrom the position shown by phantom lines in FIGURE 4 and indicated bythe letter A to an intermediate or full line position B and to a raisedposition C. In order to angle the blade about a longitudinal axis of thevehicle so that the blade moves counterclockwise to assume the positionindicated by the phantom lines in FIGURE 3, the lift jack 42 is extendedwhile jack 44 is contracted. To angle the blade in the oppositedirection, the lift jack 42 is contracted and the lift jack 44 extended.For purposes of pitching the blade forward or aft about the tranverseaxis passing through the pivotal connections 30, 32, 38 and 40, thedouble-acting tilt jack 54 can be selectively extended or contracted.

From the above description, it should be apparent that thisparallelogram linkage provides a variety of positions of the dozer bladefor accomplishing all operations required of a bulldozer. The linkage isof compact design with the main elements thereof located in positionswhich effectively transmit forces directly to the frame during thenormal dozing operation. Moreover, it will be noted that by locating thelift jacks diagonally between the lower end of the dozer blade and thevehicle, a rigid support is provided which prevents the blade from beingpulled down into the material being dug which is a common difficultyexperienced with blades during dozing operations.

Various changes and modifications can be made in this constructionwithout departing from the spirit of the invention. Such changes andmodifications are contemplated by the inventor and he does not wish tobe limited except by the scope of the appended claims.

What is claimed is:

1. In combination with a vehicle having front and rear axles,ground-engaging wheels supported on opposite ends of the respectiveaxles, a dozer assembly mounted to the front end of said vehicle, saiddozer assembly comprising a pair of transversely spaced push armspivotally connected at one end thereof to said vehicle for movementabout a first transverse pivot axis, each of said push arms beinglocated adjacent to and inboard of the front wheels, at dozer blademounted to the other end of said push arms for pivotal movement about asecond transverse axis, a first double-acting jack extending betweeneach of said push arms and said vehicle for raising and lowering saidpush arms between carry and dozing positions, means pivotally connectingone end of said jack to said push arm at a point on said secondtransverse axis, means pivotally connecting the other end of said jackto said vehicle at a point vertically spaced from said first transverseaxis, a second double-acting.

jack for tilting said blade about said second transverse axis and lyingin a plane substantially parallel to a plane passing through the pusharms, means pivotally connecting one end of said second jack to an upperportion of said dozer blade at a point vertically spaced from the secondtransverse axis, and means pivotally connecting the other end of saidsecond jack to the vehicle at a point located substantially midwaybetween the points of connections between the first jacks and thevehicle.

2. In combination with a vehicle, a dozer assembly mounted to saidvehicle, said dozer assembly comprising a pair of transversely spacedpush arms universally pivotally connected at one end thereof to oppositesides of said vehicle at points that define a first transverseaxis, adozer blade mounted to the other end of said push arms for pivotalmovement about a second transverse axis, a pair of double-acting jacksextending between said push arms and said vehicle, means universallypivotally connecting one end of each of said jacks to said push arm at apoint located on said second transverse axis, means universallypivotally connecting the other end of each of said jacks to said vehicleat a point vertically spaced from said first transverse axis, a strutmember, means universally pivotally connecting one end of said strutmember to an upper portion of said dozer blade at a point verticallyspaced from the second transverse axis, means universally pivotallyconnecting the other end of said strut member to the vehicle at a pointaxially aligned with and substantially midway between the points ofconnections of the jacks and the vehicle, and said dozer blade adaptedto be raised from a dozing position about said first transverse axiswhen said pair of jacks are concurrently contracted, and said dozerblade adapted to be angled about an axis extending longitudinally of thevehicle when one of said pair of jacks is expanded.

3. In combination with a vehicle having front and rear axles,ground-engaging wheels supported on opposite ends of the respectiveaxles, a dozer assembly mounted to the front end of said vehicle, saiddozer assembly comprising a pair of transversely spaced push armsuniversally pivotally connected at one end thereof to opposite sides ofsaid vehicle at points lying in a first transverse pivot axis, each ofsaid push arms being located ad- 'jacent to and inboard of the frontwheels, a dozer blade mounted to the other end of said push arms forpivotal movement about a second transverse axis, a pair of double-actingjacks extending between said push arms and said vehicle, meansuniversally pivotally connecting one end of each of said jacks to theassociated push arm at a point located on said second transverse axis,means universally pivotally connecting the other end of each of saidjacks to said vehicle at a point vertically spaced from said firsttransverse axis, a strut member, means universally pivotally connectingone end of said strut member to an upper portion of said dozer blade ata point vertically spaced from the second transverse axis, meansuniversally pivotally connecting the other end of said strut member tothe vehicle at a point axially aligned with and substantially midwaybetween the points of connections of the jacks and the vehiclerespectively, said dozer blade adapted to be raised from a dozingposition about said first transverse axis when said pair of jacks areconcurrently contracted, and adapted to be angled about an axisextending longitudinally of the vehicle when one of said pair of jacksis expanded and the other is contracted.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 6/ 1961Australia.

ABRAHAM G. STONE, Primary Examiner.

R. L. HOLLISTER, Assistant Examiner.

1. IN COMBINATION WITH A VEHICHLE HAVING FRONT AND REAR AXLES,GROUND-ENGAGING WHEELS SUPPORTED ON OPPOSITE ENDS OF THE RESPECTIVEAXLES, A DOZER ASSEMBLY MOUNTED TO THE FRONT END OF SAID VEHICLE, SAIDDOZER ASSEMBLY COMPRISING A PAIR OF TRANSVERSELY SPACED PUSH ARMSPIVOTALLY CONNECTED AT ONE END THEREOF TO SAID VEHICLE FOR MOVEMENT ABUTA FIRST TRANSVERSE PIVOT AXIS, EACH OF SAID PUSH ARMS BEING LOCATEDADJACENT TO AND INBOARD OF THE FRONT WHEELS, A DOZER BLADE MOUNTED TOTHE OTHER END OF SAID PUSH ARMS ARMS FOR PIVOTAL MOVEMET ABOUT A SECONDTRANSVERSE AXIS, A FIRST DOUBLE-ACTING JACK EXTENDING BETWEEN EACH OFSAID PUSH ARMS AND SAID VEHICLE FOR RAISING SAND LOWERING SAID PUSH ARMSBETWEEN CARRY AND DOZING POSITIONS, MEANS PIVOTALLY CONNECTING ONE ENDOF SAID JACK TO SAID PUSH ARM AT A POINT ON SAID SECOND TRANSVERSE AXIS,MEANS PIVOTALLY CONNECTING THE OTHER END OF SAID JACK TO SAID VEHICLE ATA POINT VERTICALLY SPACED FROM SAID FIRST TRANSVERSE AXIS, A SECONDDOUBLE-ACTING JACK FOR TILTING SAID BLADE ABOUT SAID SECOND TRANSVERSEAXIS AND LYING IN A PLANE SUBSTANTIALLY PARALLEL TO A PLANE PASSINGTHROUGH THE PUSH ARMS, MEANS PIVOTALLY CONNECTING ONE END OF SAID SECONDJACK TO AN UPPER PORTION OF SDAID DOZER BLADE AT A POINT VERTICALLYSPACED FROM THE SECOND TRANSVERSE AXIS, AND MEANS PIVOTALLY CONNECTINGTHE OTHER END OF SAID SECOND JACK TO THE VEHICLE AT A POINT LOCATEDSUBSTANTIALLY MIDWAY BETWEEN THE POINTS OF CONNECTIONS BETWEEN THE FIRSTJACKS AND THE VEHICLE.